2 1/2" #6 would make me feel underpowered even at close up and personal distance and I would rather see a minimum of 2 3/4" #4 shot instead. Save the 2 1/2" stuff for practice loads. That should still give you some protection against wall penetration while ruining the day of a hostile boogerman who is to close and to personal.
Good intentions will always be pleaded for any assumption of power. The Constitution was made to guard the people against the dangers of good intentions. There are men in all ages who mean to govern will, but they mean to govern. They promise to be good masters, but they mean to be masters.